The Research On The Degradation Of Dye Wastewater Using Pms Activated By Cofe204Immobilized On Go

Recently, the advanced oxidationn technology based on sulfate radicals has aroused people’s attention. In comparation with the traditional hydroxyl radicals, the sulfate radicals have higher redox potential, the wider range of pH application, the weaker inactivation rate, and the higher degree of mineralization and no harm to environment. Researches show that homogeneous catalytic oxidation system has faster reaction rate and simple operatation but the transition metal ion may cause the second pollution to the environment and the catalyst is hard to be recycled. Due to the shortage of the homogeneous system, the heterogeneous catalytic system make a change and effectively solve the two major drawbacks of the homogeneous catalytic system. In this paper, the CoFe2O4was supported on graphite oxide to form the composite catalyst CoFe2O4GO, and the research on the degradation of Orange II, as a model compound, based on the heterogeneous catalytic system CoFe2O4GO/PMS was studied; Also the stability of the catalyst, and the quantity of transition metal ion leached from the solution, and the effect of inorganic ions on the degradation was investigated. The major research contents as following:(1) The preparation and characterization of the catalystGO was prepared from purified natural graphite with a mean particle according to the method reported by Hummers and Offeman. Using graphite oxide as the presoma, CoFe204/GO was synthesized by hydrothermal method in water. The GO, CoFe2O4and CoFe2O4/GO was characterized by X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FT-IR), Raman, hcanning electron microscopy(SEM), high resolution transmission electron microscopy(HRTEM) and vibrating sample magnetometer(VSM). The results showed that the CoFe2O4was suppoted on GO successfully. Results show that the CoFe204/GO catalysts are large GO sheets decorated homogenously with well-despersed CoFe2O4nanoparticles. The interlayer spacing of graphene oxide(GO) is about0.796nm. The surface of GO was quite smooth and have a lot of oxygen-containing functional groups like carboxyl, hydroxyl, epoxy and so on contributed to the form of CoFe2O4/GO. The dispersed CoFe2O4with the particle of5-6nm on GO and the lattice spacing of0.3484nm can be found. (2) The activity and stability of the composite catalystThe preparative composite catalyst was applied on the research of the degradation of Orange II with the heterogeous system. The good catalytic activity of composite catalyst of CoFe2O4can be found, the optimal experimental parameters, such as pH value, the dosage of catalyst and oxidant, the operation temperature and the stability of catalyst, were studied. The the optimum operation conditions was systematically studied and optimized. The optimal operation condition for degradation of0.2mM Orange II solution is considered to be the dosage of0.15g/L CoFe204/GO and2mM PMS, pH7and25℃. Under the optimal condition,100%degradation of Orange II could be obtained within only20min, and the removal percent of COD can reached90%over180min. After4rounds of regeneration of the catalyst, the catalyst exhibited stable performance, because the reaction still can be finished within60min, and the concentration of transition metal ions leached from the solution is still very low.(3) The effect of inorganic ions on the reactionThe effect of inorganic ions with different concentrations on the reaction was studied. can activate PMS and generate H2PO5-, H2PO5-and Co2+can complex to H2PO5--Co2+, which is new active centre,so the effects of H2PO4-had positive effect on the degradation of Orange II. HCO3-had positive effect. But with the increase of concentration of HCO3-, the positive effect decreased. With low concentration of Cl", new lower active centre can be generated due to the reaction of Cl and SO4,the reaction was restrained. While with higher concentration of Cl", the quantity of Cl increased, within the same time, more Cl’can accelerate the degradation rate, the inhibiting effect of Cldecreased. NO3-can react with SO4-· and generate SO4-·, which hindered the contact between catalyst and Orange II.